Manually activated permanent magnet chucks have been in existence for many years. One of the common applications is as a work-holding device used in machining operations on grinders, lathes, and mills. Another application is a mechanical lifter for material handling purposes. These permanent magnet chucks usually have relatively low levels of attractive force and their load carrying capacities are somewhat limited. Consequently, the magnetic chucks are very bulky in their physical dimensions and have large surface contact areas in order to meet their performance targets.
Typically permanent magnet chucks have a movable magnet portion that must be rotated from an inactive position to a magnetically active position for use of the chuck. In prior designs, activation of the chuck is often accomplished by actuation of a lever on the side of the device. Typically the arrangement of the magnets in the chuck is such that the actuating lever must be moved through a large angle of rotation, typically ranging from 120° to 180°. These conditions pose physical obstructions in many practical workplace applications where there is not room for the sweeping reach of such a side-located lever.